The abyssal halosaur (''Halosauropsis macrochir'') is a species of bottom-dwelling,
deep-sea fish
Deep-sea fish are fish that live in the darkness below the sunlit surface waters, that is below the epipelagic or photic zone of the sea. The lanternfish is, by far, the most common deep-sea fish. Other deep sea fishes include the flashlight ...
in the family
Halosauridae
Halosaurs are eel-shaped fishes found only at great ocean depths. As the family Halosauridae, halosaurs are one of two families within the order Notacanthiformes; the other being the deep-sea spiny eels, Notacanthidae. Halosaurs are thought to h ...
that is found in all oceans at depths of 1100 to 3500 meters. It is the only member of its
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
.
Abyssal halosaur can reach total length of at least and weight in excess of . Berstad et al. could not sex fish smaller than 25 cm, giving an indication about length at maturation. Abyssal halosaur are long-lived, with maximum reported age of 36 years, although individuals sampled on the
Mid-Atlantic Ridge
The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North Ame ...
were mostly <20 years. It appears to be an opportunistic feeder, mostly taking